finish porting to new parser

src/ast.rs

@@ -1,154 +1,148 @@
-#[derive(Debug, Clone, Copy)]
-pub struct Position(pub usize);
+use crate::Span;
 
 #[derive(Debug)]
-pub struct Script<'a> {
-    pub imports: Vec<Import<'a>>,
-    pub global_vars: Vec<GlobalVar<'a>>,
-    pub functions: Vec<Function<'a>>,
+pub struct Script {
+    pub imports: Vec<Import>,
+    pub global_vars: Vec<GlobalVar>,
+    pub functions: Vec<Function>,
 }
 
 #[derive(Debug)]
-pub enum TopLevelItem<'a> {
-    Import(Import<'a>),
-    GlobalVar(GlobalVar<'a>),
-    Function(Function<'a>),
+pub enum TopLevelItem {
+    Import(Import),
+    GlobalVar(GlobalVar),
+    Function(Function),
 }
 
 #[derive(Debug)]
-pub struct Import<'a> {
-    pub position: Position,
-    pub import: &'a str,
-    pub type_: ImportType<'a>,
+pub struct Import {
+    pub span: Span,
+    pub import: String,
+    pub type_: ImportType,
 }
 
 #[derive(Debug)]
-pub enum ImportType<'a> {
+pub enum ImportType {
     Memory(u32),
     Variable {
-        name: &'a str,
+        name: String,
         type_: Type,
         mutable: bool,
     },
-    // Function { name: &'a str, params: Vec<Type>, result: Option<Type> }
+    // Function { name: String, params: Vec<Type>, result: Option<Type> }
 }
 
 #[derive(Debug)]
-pub struct GlobalVar<'a> {
-    pub position: Position,
-    pub name: &'a str,
+pub struct GlobalVar {
+    pub span: Span,
+    pub name: String,
     pub type_: Type,
 }
 
 #[derive(Debug)]
-pub struct Function<'a> {
-    pub position: Position,
+pub struct Function {
+    pub span: Span,
     pub export: bool,
-    pub name: &'a str,
-    pub params: Vec<(&'a str, Type)>,
+    pub name: String,
+    pub params: Vec<(String, Type)>,
     pub type_: Option<Type>,
-    pub body: Block<'a>,
+    pub body: Block,
 }
 
 #[derive(Debug)]
-pub struct Block<'a> {
-    pub statements: Vec<Statement<'a>>,
-    pub final_expression: Option<Expression<'a>>,
+pub struct Block {
+    pub statements: Vec<Expression>,
+    pub final_expression: Option<Box<Expression>>,
 }
 
-impl<'a> Block<'a> {
+impl Block {
     pub fn type_(&self) -> Option<Type> {
         self.final_expression.as_ref().and_then(|e| e.type_)
     }
 }
 
 #[derive(Debug)]
-pub enum Statement<'a> {
-    LocalVariable(LocalVariable<'a>),
-    Poke {
-        position: Position,
-        mem_location: MemoryLocation<'a>,
-        value: Expression<'a>,
-    },
-    Expression(Expression<'a>),
-}
-
-#[derive(Debug)]
-pub struct MemoryLocation<'a> {
-    pub position: Position,
+pub struct MemoryLocation {
+    pub span: Span,
     pub size: MemSize,
-    pub left: Expression<'a>,
-    pub right: Expression<'a>,
+    pub left: Box<Expression>,
+    pub right: Box<Expression>,
 }
 
 #[derive(Debug)]
-pub struct LocalVariable<'a> {
-    pub position: Position,
-    pub name: &'a str,
+pub struct Expression {
     pub type_: Option<Type>,
-    pub value: Option<Expression<'a>>,
-    pub defer: bool
+    pub expr: Expr,
+    pub span: Span,
 }
 
 #[derive(Debug)]
-pub struct Expression<'a> {
-    pub type_: Option<Type>,
-    pub expr: Expr<'a>,
-}
-
-impl<'a> From<Expr<'a>> for Expression<'a> {
-    fn from(expr: Expr<'a>) -> Expression<'a> {
-        Expression { type_: None, expr }
-    }
-}
-
-#[derive(Debug)]
-pub enum Expr<'a> {
+pub enum Expr {
     I32Const(i32),
     F32Const(f32),
-    Variable {
-        position: Position,
-        name: &'a str,
+    Variable(String),
+    Let {
+        name: String,
+        type_: Option<Type>,
+        value: Option<Box<Expression>>,
+        defer: bool,
+    },
+    Poke {
+        mem_location: MemoryLocation,
+        value: Box<Expression>,
     },
     Loop {
-        position: Position,
-        label: &'a str,
-        block: Box<Block<'a>>,
+        label: String,
+        block: Box<Block>,
     },
     BranchIf {
-        position: Position,
-        condition: Box<Expression<'a>>,
-        label: &'a str,
+        condition: Box<Expression>,
+        label: String,
+    },
+    UnaryOp {
+        op: UnaryOp,
+        value: Box<Expression>,
     },
     BinOp {
-        position: Position,
         op: BinOp,
-        left: Box<Expression<'a>>,
-        right: Box<Expression<'a>>,
+        left: Box<Expression>,
+        right: Box<Expression>,
     },
     LocalTee {
-        position: Position,
-        name: &'a str,
-        value: Box<Expression<'a>>,
+        name: String,
+        value: Box<Expression>,
     },
     Cast {
-        position: Position,
-        value: Box<Expression<'a>>,
+        value: Box<Expression>,
         type_: Type,
     },
     FuncCall {
-        position: Position,
-        name: &'a str,
-        params: Vec<Expression<'a>>
+        name: String,
+        params: Vec<Expression>,
     },
     Select {
-        position: Position,
-        condition: Box<Expression<'a>>,
-        if_true: Box<Expression<'a>>,
-        if_false: Box<Expression<'a>>
+        condition: Box<Expression>,
+        if_true: Box<Expression>,
+        if_false: Box<Expression>,
+    },
+    Error,
+}
+
+impl Expr {
+    pub fn with_span(self, span: Span) -> Expression {
+        Expression {
+            type_: None,
+            expr: self,
+            span: span,
+        }
     }
 }
 
+#[derive(Debug, Clone, Copy)]
+pub enum UnaryOp {
+    Negate,
+}
+
 #[derive(Debug, Clone, Copy)]
 pub enum BinOp {
     Add,

src/constfold.rs

@@ -8,22 +8,7 @@ pub fn fold_script(script: &mut ast::Script) {
 
 fn fold_block(block: &mut ast::Block) {
     for stmt in &mut block.statements {
-        match stmt {
-            ast::Statement::LocalVariable(lv) => {
-                if let Some(ref mut expr) = lv.value {
-                    fold_expr(expr);
-                }
-            }
-            ast::Statement::Expression(expr) => fold_expr(expr),
-            ast::Statement::Poke {
-                mem_location,
-                value,
-                ..
-            } => {
-                fold_mem_location(mem_location);
-                fold_expr(value);
-            }
-        }
+        fold_expr(stmt);
     }
     if let Some(ref mut expr) = block.final_expression {
         fold_expr(expr);
@@ -38,6 +23,29 @@ fn fold_mem_location(mem_location: &mut ast::MemoryLocation) {
 fn fold_expr(expr: &mut ast::Expression) {
     use ast::BinOp::*;
     match expr.expr {
+        ast::Expr::Let { ref mut value, .. } => {
+            if let Some(ref mut expr) = value {
+                fold_expr(expr);
+            }
+        }
+        ast::Expr::Poke {
+            ref mut mem_location,
+            ref mut value,
+            ..
+        } => {
+            fold_mem_location(mem_location);
+            fold_expr(value);
+        }
+        ast::Expr::UnaryOp { op, ref mut value } => {
+            fold_expr(value);
+            let result = match (op, &value.expr) {
+                (ast::UnaryOp::Negate, ast::Expr::I32Const(value)) => Some(ast::Expr::I32Const(-*value)),
+                _ => None
+            };
+            if let Some(result) = result {
+                expr.expr = result;
+            }
+        }
         ast::Expr::BinOp {
             ref mut left,
             op,
@@ -105,7 +113,7 @@ fn fold_expr(expr: &mut ast::Expression) {
         } => fold_expr(condition),
         ast::Expr::Cast { ref mut value, .. } => fold_expr(value),
         ast::Expr::FuncCall {
-            name,
+            ref name,
             ref mut params,
             ..
         } => {
@@ -114,15 +122,21 @@ fn fold_expr(expr: &mut ast::Expression) {
             }
             use ast::Expr::*;
             let params: Vec<_> = params.iter().map(|e| &e.expr).collect();
-            expr.expr = match (name, params.as_slice()) {
+            expr.expr = match (name.as_str(), params.as_slice()) {
                 ("sqrt", [F32Const(v)]) if *v >= 0.0 => F32Const(v.sqrt()),
                 _ => return,
             };
         }
-        ast::Expr::Select { ref mut condition, ref mut if_true, ref mut if_false, .. } => {
+        ast::Expr::Select {
+            ref mut condition,
+            ref mut if_true,
+            ref mut if_false,
+            ..
+        } => {
             fold_expr(condition);
             fold_expr(if_true);
             fold_expr(if_false);
         }
+        ast::Expr::Error => unreachable!()
     }
 }

src/emit.rs

@@ -35,7 +35,7 @@ pub fn emit(script: &ast::Script) -> Vec<u8> {
                     Some(&import.import[(dot_index + 1)..]),
                 )
             } else {
-                (import.import, None)
+                (import.import.as_str(), None)
             };
             let type_: EntityType = match import.type_ {
                 ast::ImportType::Memory(min_size) => MemoryType {
@@ -46,7 +46,7 @@ pub fn emit(script: &ast::Script) -> Vec<u8> {
                 .into(),
                 ast::ImportType::Variable {
                     type_,
-                    name,
+                    ref name,
                     mutable,
                 } => {
                     globals.insert(name, globals.len() as u32);
@@ -72,7 +72,7 @@ pub fn emit(script: &ast::Script) -> Vec<u8> {
             let type_ = *function_types.get(&function_type_key(func)).unwrap();
             functions.function(type_ as u32);
             if func.export {
-                exports.export(func.name, Export::Function(index as u32));
+                exports.export(&func.name, Export::Function(index as u32));
             }
 
             code.function(&emit_function(func, &globals));
@@ -109,9 +109,9 @@ fn function_type_key(func: &ast::Function) -> FunctionTypeKey {
 struct FunctionContext<'a> {
     function: &'a mut Function,
     globals: &'a HashMap<&'a str, u32>,
-    locals: &'a HashMap<&'a str, u32>,
+    locals: &'a HashMap<String, u32>,
     labels: Vec<String>,
-    deferred_inits: HashMap<&'a str, &'a ast::Expression<'a>>,
+    deferred_inits: HashMap<&'a str, &'a ast::Expression>,
 }
 
 fn emit_function(func: &ast::Function, globals: &HashMap<&str, u32>) -> Function {
@@ -121,7 +121,7 @@ fn emit_function(func: &ast::Function, globals: &HashMap<&str, u32>) -> Function
 
     let mut function = Function::new_with_locals_types(locals.iter().map(|(_, t)| map_type(*t)));
 
-    let locals: HashMap<&str, u32> = locals
+    let locals: HashMap<String, u32> = locals
         .into_iter()
         .enumerate()
         .map(|(index, (name, _))| (name, index as u32))
@@ -144,34 +144,33 @@ fn emit_function(func: &ast::Function, globals: &HashMap<&str, u32>) -> Function
     function
 }
 
-fn collect_locals<'a>(block: &ast::Block<'a>, locals: &mut Vec<(&'a str, ast::Type)>) {
+fn collect_locals<'a>(block: &ast::Block, locals: &mut Vec<(String, ast::Type)>) {
     for stmt in &block.statements {
-        match stmt {
-            ast::Statement::LocalVariable(v) => {
-                locals.push((v.name, v.type_.unwrap()));
-                if let Some(ref value) = v.value {
-                    collect_locals_expr(value, locals);
-                }
-            }
-            ast::Statement::Expression(e) => collect_locals_expr(e, locals),
-            ast::Statement::Poke {
-                mem_location,
-                value,
-                ..
-            } => {
-                collect_locals_expr(&mem_location.left, locals);
-                collect_locals_expr(value, locals);
-            }
-        }
+        collect_locals_expr(stmt, locals);
     }
     if let Some(ref expr) = block.final_expression {
         collect_locals_expr(expr, locals);
     }
 }
 
-fn collect_locals_expr<'a>(expr: &ast::Expression<'a>, locals: &mut Vec<(&'a str, ast::Type)>) {
+fn collect_locals_expr<'a>(expr: &ast::Expression, locals: &mut Vec<(String, ast::Type)>) {
     match &expr.expr {
+        ast::Expr::Let {name, type_, value, ..} => {
+            locals.push((name.clone(), type_.unwrap()));
+            if let Some(ref value) = value {
+                collect_locals_expr(value, locals);
+            }
+        }
+        ast::Expr::Poke {
+            mem_location,
+            value,
+            ..
+        } => {
+            collect_locals_expr(&mem_location.left, locals);
+            collect_locals_expr(value, locals);
+        }
         ast::Expr::Variable { .. } | ast::Expr::I32Const(_) | ast::Expr::F32Const(_) => (),
+        ast::Expr::UnaryOp { value, .. } => collect_locals_expr(value, locals),
         ast::Expr::BinOp { left, right, .. } => {
             collect_locals_expr(left, locals);
             collect_locals_expr(right, locals);
@@ -195,54 +194,15 @@ fn collect_locals_expr<'a>(expr: &ast::Expression<'a>, locals: &mut Vec<(&'a str
             collect_locals_expr(if_true, locals);
             collect_locals_expr(if_false, locals);
         }
+        ast::Expr::Error => unreachable!()
     }
 }
 
 fn emit_block<'a>(ctx: &mut FunctionContext<'a>, block: &'a ast::Block) {
     for stmt in &block.statements {
-        match stmt {
-            ast::Statement::Expression(e) => {
-                emit_expression(ctx, e);
-                if e.type_.is_some() {
-                    ctx.function.instruction(&Instruction::Drop);
-                }
-            }
-            ast::Statement::LocalVariable(v) => {
-                if let Some(ref val) = v.value {
-                    if v.defer {
-                        ctx.deferred_inits.insert(v.name, val);
-                    } else {
-                        emit_expression(ctx, val);
-                        ctx.function
-                            .instruction(&Instruction::LocalSet(*ctx.locals.get(v.name).unwrap()));
-                    }
-                }
-            }
-            ast::Statement::Poke {
-                mem_location,
-                value,
-                ..
-            } => {
-                emit_expression(ctx, &mem_location.left);
-                emit_expression(ctx, value);
-                let offset = if let ast::Expr::I32Const(v) = mem_location.right.expr {
-                    v as u32 as u64
-                } else {
-                    unreachable!()
-                };
-                ctx.function.instruction(&match mem_location.size {
-                    ast::MemSize::Byte => Instruction::I32Store8(MemArg {
-                        align: 0,
-                        memory_index: 0,
-                        offset,
-                    }),
-                    ast::MemSize::Word => Instruction::I32Store(MemArg {
-                        align: 2,
-                        memory_index: 0,
-                        offset,
-                    }),
-                });
-            }
+        emit_expression(ctx, stmt);
+        if stmt.type_.is_some() {
+            ctx.function.instruction(&Instruction::Drop);
         }
     }
     if let Some(ref expr) = block.final_expression {
@@ -252,6 +212,55 @@ fn emit_block<'a>(ctx: &mut FunctionContext<'a>, block: &'a ast::Block) {
 
 fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression) {
     match &expr.expr {
+        ast::Expr::Let { value, name, defer, ..}  => {
+            if let Some(ref val) = value {
+                if *defer {
+                    ctx.deferred_inits.insert(name, val);
+                } else {
+                    emit_expression(ctx, val);
+                    ctx.function
+                        .instruction(&Instruction::LocalSet(*ctx.locals.get(name).unwrap()));
+                }
+            }
+        }
+        ast::Expr::Poke {
+            mem_location,
+            value,
+            ..
+        } => {
+            emit_expression(ctx, &mem_location.left);
+            emit_expression(ctx, value);
+            let offset = if let ast::Expr::I32Const(v) = mem_location.right.expr {
+                v as u32 as u64
+            } else {
+                unreachable!()
+            };
+            ctx.function.instruction(&match mem_location.size {
+                ast::MemSize::Byte => Instruction::I32Store8(MemArg {
+                    align: 0,
+                    memory_index: 0,
+                    offset,
+                }),
+                ast::MemSize::Word => Instruction::I32Store(MemArg {
+                    align: 2,
+                    memory_index: 0,
+                    offset,
+                }),
+            });
+        }
+        ast::Expr::UnaryOp { op, value } => {
+            use ast::UnaryOp::*;
+            use ast::Type::*;
+            match (value.type_.unwrap(), op) {
+                (I32, Negate) => {
+                    // TODO: try to improve this uglyness
+                    ctx.function.instruction(&Instruction::I32Const(0));
+                    emit_expression(ctx, value);
+                    ctx.function.instruction(&Instruction::I32Sub);
+                }
+                _ => unreachable!()
+            };
+        }
         ast::Expr::BinOp {
             left, op, right, ..
         } => {
@@ -300,7 +309,7 @@ fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression)
                 .iter()
                 .rev()
                 .enumerate()
-                .find(|(_, l)| l == label)
+                .find(|(_, l)| *l == label)
                 .unwrap()
                 .0;
             ctx.function.instruction(&Instruction::BrIf(depth as u32));
@@ -313,7 +322,7 @@ fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression)
         }
         ast::Expr::LocalTee { name, value, .. } => {
             emit_expression(ctx, value);
-            let index = ctx.locals.get(*name).unwrap();
+            let index = ctx.locals.get(name).unwrap();
             ctx.function.instruction(&Instruction::LocalTee(*index));
         }
         ast::Expr::Loop { label, block, .. } => {
@@ -324,15 +333,15 @@ fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression)
             ctx.labels.pop();
             ctx.function.instruction(&Instruction::End);
         }
-        ast::Expr::Variable { name, .. } => {
-            if let Some(index) = ctx.locals.get(*name) {
-                if let Some(expr) = ctx.deferred_inits.remove(*name) {
+        ast::Expr::Variable(name) => {
+            if let Some(index) = ctx.locals.get(name) {
+                if let Some(expr) = ctx.deferred_inits.remove(name.as_str()) {
                     emit_expression(ctx, expr);
                     ctx.function.instruction(&Instruction::LocalTee(*index));
                 } else {
                     ctx.function.instruction(&Instruction::LocalGet(*index));
                 }
-            } else if let Some(index) = ctx.globals.get(*name) {
+            } else if let Some(index) = ctx.globals.get(name.as_str()) {
                 ctx.function.instruction(&Instruction::GlobalGet(*index));
             } else {
                 unreachable!()
@@ -371,6 +380,7 @@ fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression)
             emit_expression(ctx, condition);
             ctx.function.instruction(&Instruction::Select);
         }
+        ast::Expr::Error => unreachable!()
     }
 }
 

src/main.rs

@@ -6,9 +6,10 @@ mod ast;
 mod constfold;
 mod emit;
 mod parser;
-mod parser2;
 mod typecheck;
 
+type Span = std::ops::Range<usize>;
+
 fn main() -> Result<()> {
     let mut filename = PathBuf::from(
         std::env::args()
@@ -18,28 +19,14 @@ fn main() -> Result<()> {
     let mut input = String::new();
     File::open(&filename)?.read_to_string(&mut input)?;
 
-    if let Err(_) = parser2::parse(&input) {
-        bail!("Parse failed");
-    }
-
-    let mut script = match parser::parse(input.as_str()) {
+    let mut script = match parser::parse(&input) {
         Ok(script) => script,
-        Err(err) => {
-            bail!(
-                "parse error: {}",
-                nom::error::convert_error(input.as_str(), err)
-            );
-        }
+        Err(_) => bail!("Parse failed")
     };
 
     constfold::fold_script(&mut script);
-    if let Err(err) = typecheck::tc_script(&mut script) {
-        let line = input[..(input.len() - err.position.0)]
-            .chars()
-            .filter(|c| *c == '\n')
-            .count()
-            + 1;
-        bail!("{} in line {}", err.message, line);
+    if let Err(_) = typecheck::tc_script(&mut script, &input) {
+        bail!("Parse failed");
     }
     let wasm = emit::emit(&script);
 

src/parser2.rs

@@ -1,830 +0,0 @@
-use ariadne::{Color, Fmt, Label, Report, ReportKind, Source};
-use chumsky::{prelude::*, stream::Stream};
-use std::fmt;
-
-pub type Span = std::ops::Range<usize>;
-
-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
-enum Token {
-    Import,
-    Export,
-    Fn,
-    Let,
-    Memory,
-    Global,
-    Mut,
-    Loop,
-    BranchIf,
-    Defer,
-    As,
-    Select,
-    Ident(String),
-    Str(String),
-    Int(i32),
-    Float(String),
-    Op(String),
-    Ctrl(char),
-}
-
-impl fmt::Display for Token {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            Token::Import => write!(f, "import"),
-            Token::Export => write!(f, "export"),
-            Token::Fn => write!(f, "fn"),
-            Token::Let => write!(f, "let"),
-            Token::Memory => write!(f, "memory"),
-            Token::Global => write!(f, "global"),
-            Token::Mut => write!(f, "mut"),
-            Token::Loop => write!(f, "loop"),
-            Token::BranchIf => write!(f, "branch_if"),
-            Token::Defer => write!(f, "defer"),
-            Token::As => write!(f, "as"),
-            Token::Select => write!(f, "select"),
-            Token::Ident(s) => write!(f, "{}", s),
-            Token::Str(s) => write!(f, "{:?}", s),
-            Token::Int(v) => write!(f, "{}", v),
-            Token::Float(v) => write!(f, "{}", v),
-            Token::Op(s) => write!(f, "{}", s),
-            Token::Ctrl(c) => write!(f, "{}", c),
-        }
-    }
-}
-
-pub fn parse(source: &str) -> Result<(), ()> {
-    let tokens = match lexer().parse(source) {
-        Ok(tokens) => tokens,
-        Err(errors) => {
-            report_errors(
-                errors
-                    .into_iter()
-                    .map(|e| e.map(|c| c.to_string()))
-                    .collect(),
-                source,
-            );
-            return Err(());
-        }
-    };
-
-    let source_len = source.chars().count();
-    let script = match script_parser().parse(Stream::from_iter(
-        source_len..source_len + 1,
-        tokens.into_iter(),
-    )) {
-        Ok(script) => script,
-        Err(errors) => {
-            report_errors(
-                errors
-                    .into_iter()
-                    .map(|e| e.map(|t| t.to_string()))
-                    .collect(),
-                source,
-            );
-            return Err(());
-        }
-    };
-    dbg!(script);
-    Ok(())
-}
-
-fn report_errors(errors: Vec<Simple<String>>, source: &str) {
-    for error in errors {
-        let report = Report::build(ReportKind::Error, (), error.span().start());
-
-        let report = match error.reason() {
-            chumsky::error::SimpleReason::Unclosed { span, delimiter } => report
-                .with_message(format!(
-                    "Unclosed delimiter {}",
-                    delimiter.fg(Color::Yellow)
-                ))
-                .with_label(
-                    Label::new(span.clone())
-                        .with_message(format!(
-                            "Unclosed delimiter {}",
-                            delimiter.fg(Color::Yellow)
-                        ))
-                        .with_color(Color::Yellow),
-                )
-                .with_label(
-                    Label::new(error.span())
-                        .with_message(format!(
-                            "Must be closed before this {}",
-                            error
-                                .found()
-                                .unwrap_or(&"end of file".to_string())
-                                .fg(Color::Red)
-                        ))
-                        .with_color(Color::Red),
-                ),
-            chumsky::error::SimpleReason::Unexpected => report
-                .with_message(format!(
-                    "{}, expected one of {}",
-                    if error.found().is_some() {
-                        "Unexpected token in input"
-                    } else {
-                        "Unexpted end of input"
-                    },
-                    if error.expected().len() == 0 {
-                        "end of input".to_string()
-                    } else {
-                        error
-                            .expected()
-                            .map(|x| x.to_string())
-                            .collect::<Vec<_>>()
-                            .join(", ")
-                    }
-                ))
-                .with_label(
-                    Label::new(error.span())
-                        .with_message(format!(
-                            "Unexpected token {}",
-                            error
-                                .found()
-                                .unwrap_or(&"end of file".to_string())
-                                .fg(Color::Red)
-                        ))
-                        .with_color(Color::Red),
-                ),
-            chumsky::error::SimpleReason::Custom(msg) => report.with_message(msg).with_label(
-                Label::new(error.span())
-                    .with_message(format!("{}", msg.fg(Color::Red)))
-                    .with_color(Color::Red),
-            ),
-        };
-
-        report.finish().eprint(Source::from(source)).unwrap();
-    }
-}
-
-fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = Simple<char>> {
-    let float = text::int(10)
-        .chain::<char, _, _>(just('.').chain(text::digits(10)))
-        .collect::<String>()
-        .map(Token::Float);
-
-    let int = text::int(10).map(|s: String| Token::Int(s.parse().unwrap()));
-
-    let str_ = just('"')
-        .ignore_then(filter(|c| *c != '"').repeated())
-        .then_ignore(just('"'))
-        .collect::<String>()
-        .map(Token::Str);
-
-    let op = one_of("+-*/%&^|<=>".chars())
-        .repeated()
-        .at_least(1)
-        .or(just(':').chain(just('=')))
-        .collect::<String>()
-        .map(Token::Op);
-
-    let ctrl = one_of("(){};,:?!".chars()).map(Token::Ctrl);
-
-    let ident = text::ident().map(|ident: String| match ident.as_str() {
-        "import" => Token::Import,
-        "export" => Token::Export,
-        "fn" => Token::Fn,
-        "let" => Token::Let,
-        "memory" => Token::Memory,
-        "global" => Token::Global,
-        "mut" => Token::Mut,
-        "loop" => Token::Loop,
-        "branch_if" => Token::BranchIf,
-        "defer" => Token::Defer,
-        "as" => Token::As,
-        "select" => Token::Select,
-        _ => Token::Ident(ident),
-    });
-
-    let single_line =
-        seq::<_, _, Simple<char>>("//".chars()).then_ignore(take_until(text::newline()));
-
-    let multi_line =
-        seq::<_, _, Simple<char>>("/*".chars()).then_ignore(take_until(seq("*/".chars())));
-
-    let comment = single_line.or(multi_line);
-
-    let token = float
-        .or(int)
-        .or(str_)
-        .or(op)
-        .or(ctrl)
-        .or(ident)
-        .recover_with(skip_then_retry_until([]));
-
-    token
-        .map_with_span(|tok, span| (tok, span))
-        .padded()
-        .padded_by(comment.padded().repeated())
-        .repeated()
-}
-
-mod ast {
-    use super::Span;
-
-    #[derive(Debug)]
-    pub struct Script {
-        pub imports: Vec<Import>,
-        pub global_vars: Vec<GlobalVar>,
-        pub functions: Vec<Function>,
-    }
-
-    #[derive(Debug)]
-    pub enum TopLevelItem {
-        Import(Import),
-        GlobalVar(GlobalVar),
-        Function(Function),
-    }
-
-    #[derive(Debug)]
-    pub struct Import {
-        pub span: Span,
-        pub import: String,
-        pub type_: ImportType,
-    }
-
-    #[derive(Debug)]
-    pub enum ImportType {
-        Memory(u32),
-        Variable {
-            name: String,
-            type_: Type,
-            mutable: bool,
-        },
-        // Function { name: String, params: Vec<Type>, result: Option<Type> }
-    }
-
-    #[derive(Debug)]
-    pub struct GlobalVar {
-        pub span: Span,
-        pub name: String,
-        pub type_: Type,
-    }
-
-    #[derive(Debug)]
-    pub struct Function {
-        pub span: Span,
-        pub export: bool,
-        pub name: String,
-        pub params: Vec<(String, Type)>,
-        pub type_: Option<Type>,
-        pub body: Block,
-    }
-
-    #[derive(Debug)]
-    pub struct Block {
-        pub statements: Vec<Expression>,
-        pub final_expression: Option<Box<Expression>>,
-    }
-
-    impl Block {
-        pub fn type_(&self) -> Option<Type> {
-            self.final_expression.as_ref().and_then(|e| e.type_)
-        }
-    }
-
-    #[derive(Debug)]
-    pub struct MemoryLocation {
-        pub span: Span,
-        pub size: MemSize,
-        pub left: Box<Expression>,
-        pub right: Box<Expression>,
-    }
-
-    #[derive(Debug)]
-    pub struct LocalVariable {
-        pub span: Span,
-        pub name: String,
-        pub type_: Option<Type>,
-        pub value: Option<Expression>,
-        pub defer: bool,
-    }
-
-    #[derive(Debug)]
-    pub struct Expression {
-        pub type_: Option<Type>,
-        pub expr: Expr,
-        pub span: Span,
-    }
-
-    #[derive(Debug)]
-    pub enum Expr {
-        I32Const(i32),
-        F32Const(f32),
-        Variable(String),
-        Let {
-            name: String,
-            type_: Option<Type>,
-            value: Option<Box<Expression>>,
-            defer: bool,
-        },
-        Poke {
-            mem_location: MemoryLocation,
-            value: Box<Expression>,
-        },
-        Loop {
-            label: String,
-            block: Box<Block>,
-        },
-        BranchIf {
-            condition: Box<Expression>,
-            label: String,
-        },
-        UnaryOp {
-            op: UnaryOp,
-            value: Box<Expression>,
-        },
-        BinOp {
-            op: BinOp,
-            left: Box<Expression>,
-            right: Box<Expression>,
-        },
-        LocalTee {
-            name: String,
-            value: Box<Expression>,
-        },
-        Cast {
-            value: Box<Expression>,
-            type_: Type,
-        },
-        FuncCall {
-            name: String,
-            params: Vec<Expression>,
-        },
-        Select {
-            condition: Box<Expression>,
-            if_true: Box<Expression>,
-            if_false: Box<Expression>,
-        },
-        Error,
-    }
-
-    impl Expr {
-        pub fn with_span(self, span: Span) -> Expression {
-            Expression {
-                type_: None,
-                expr: self,
-                span: span,
-            }
-        }
-    }
-
-    #[derive(Debug, Clone, Copy)]
-    pub enum UnaryOp {
-        Negate,
-    }
-
-    #[derive(Debug, Clone, Copy)]
-    pub enum BinOp {
-        Add,
-        Sub,
-        Mul,
-        Div,
-        Rem,
-        And,
-        Or,
-        Xor,
-        Eq,
-        Ne,
-        Gt,
-        Ge,
-        Lt,
-        Le,
-    }
-
-    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
-    pub enum MemSize {
-        Byte,
-        Word,
-    }
-
-    #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Ord, PartialOrd)]
-    pub enum Type {
-        I32,
-        I64,
-        F32,
-        F64,
-    }
-}
-
-fn map_token<O>(
-    f: impl Fn(&Token) -> Option<O> + 'static + Clone,
-) -> impl Parser<Token, O, Error = Simple<Token>> + Clone {
-    filter_map(move |span, tok: Token| {
-        if let Some(output) = f(&tok) {
-            Ok(output)
-        } else {
-            Err(Simple::expected_input_found(span, Vec::new(), Some(tok)))
-        }
-    })
-}
-
-fn block_parser() -> impl Parser<Token, ast::Block, Error = Simple<Token>> + Clone {
-    recursive(|block| {
-        let mut block_expression = None;
-        let expression = recursive(|expression| {
-            let val = map_token(|tok| match tok {
-                Token::Int(v) => Some(ast::Expr::I32Const(*v)),
-                Token::Float(v) => Some(ast::Expr::F32Const(v.parse().unwrap())),
-                _ => None,
-            })
-            .labelled("value");
-
-            let variable = filter_map(|span, tok| match tok {
-                Token::Ident(id) => Ok(ast::Expr::Variable(id)),
-                _ => Err(Simple::expected_input_found(span, Vec::new(), Some(tok))),
-            })
-            .labelled("variable");
-
-            let ident = filter_map(|span, tok| match tok {
-                Token::Ident(id) => Ok(id),
-                _ => Err(Simple::expected_input_found(span, Vec::new(), Some(tok))),
-            })
-            .labelled("identifier");
-
-            let local_tee = ident
-                .then(just(Token::Op(":=".to_string())).ignore_then(expression.clone()))
-                .map(|(name, expr)| ast::Expr::LocalTee {
-                    name,
-                    value: Box::new(expr),
-                }).boxed();
-
-            let loop_expr = just(Token::Loop)
-                .ignore_then(ident)
-                .then(
-                    block
-                        .clone()
-                        .delimited_by(Token::Ctrl('{'), Token::Ctrl('}')),
-                )
-                .map(|(label, block)| ast::Expr::Loop {
-                    label,
-                    block: Box::new(block),
-                });
-
-            let block_expr = loop_expr.boxed();
-
-            block_expression = Some(block_expr.clone());
-
-            let branch_if = just(Token::BranchIf)
-                .ignore_then(expression.clone())
-                .then_ignore(just(Token::Ctrl(':')))
-                .then(ident)
-                .map(|(condition, label)| ast::Expr::BranchIf {
-                    condition: Box::new(condition),
-                    label,
-                }).boxed();
-
-            let let_ = just(Token::Let)
-                .ignore_then(just(Token::Defer).or_not())
-                .then(ident.clone())
-                .then(just(Token::Ctrl(':')).ignore_then(type_parser()).or_not())
-                .then(
-                    just(Token::Op("=".to_string()))
-                        .ignore_then(expression.clone())
-                        .or_not(),
-                )
-                .map(|(((defer, name), type_), value)| ast::Expr::Let {
-                    name,
-                    type_,
-                    value: value.map(Box::new),
-                    defer: defer.is_some(),
-                }).boxed();
-
-            let tee = ident
-                .clone()
-                .then_ignore(just(Token::Op(":=".to_string())))
-                .then(expression.clone())
-                .map(|(name, value)| ast::Expr::LocalTee {
-                    name,
-                    value: Box::new(value),
-                }).boxed();
-
-            let select = just(Token::Select)
-                .ignore_then(
-                    expression
-                        .clone()
-                        .then_ignore(just(Token::Ctrl(',')))
-                        .then(expression.clone())
-                        .then_ignore(just(Token::Ctrl(',')))
-                        .then(expression.clone())
-                        .delimited_by(Token::Ctrl('('), Token::Ctrl(')')),
-                )
-                .map(|((condition, if_true), if_false)| ast::Expr::Select {
-                    condition: Box::new(condition),
-                    if_true: Box::new(if_true),
-                    if_false: Box::new(if_false),
-                }).boxed();
-
-            let function_call = ident
-                .clone()
-                .then(
-                    expression
-                        .clone()
-                        .separated_by(just(Token::Ctrl(',')))
-                        .delimited_by(Token::Ctrl('('), Token::Ctrl(')')),
-                )
-                .map(|(name, params)| ast::Expr::FuncCall { name, params }).boxed();
-
-            let atom = val
-                .or(tee)
-                .or(function_call)
-                .or(variable)
-                .or(local_tee)
-                .or(block_expr)
-                .or(branch_if)
-                .or(let_)
-                .or(select)
-                .map_with_span(|expr, span| expr.with_span(span))
-                .or(expression
-                    .clone()
-                    .delimited_by(Token::Ctrl('('), Token::Ctrl(')')))
-                .recover_with(nested_delimiters(
-                    Token::Ctrl('('),
-                    Token::Ctrl(')'),
-                    [(Token::Ctrl('{'), Token::Ctrl('}'))],
-                    |span| ast::Expr::Error.with_span(span),
-                )).boxed();
-            
-            let unary_op = just(Token::Op("-".to_string()))
-                .to(ast::UnaryOp::Negate)
-                .map_with_span(|op, span| (op, span))
-                .repeated()
-                .then(atom)
-                .map(|(ops, value)| {
-                    ops.into_iter().rev().fold(value, |acc, (op, span)| {
-                        let span = span.start..acc.span.end;
-                        ast::Expr::UnaryOp {
-                            op,
-                            value: Box::new(acc),
-                        }
-                        .with_span(span)
-                    })
-                }).boxed();
-
-            let op_cast = unary_op
-                .clone()
-                .then(
-                    just(Token::As)
-                        .ignore_then(type_parser())
-                        .map_with_span(|type_, span| (type_, span))
-                        .repeated(),
-                )
-                .foldl(|value, (type_, span)| {
-                    ast::Expr::Cast {
-                        value: Box::new(value),
-                        type_,
-                    }
-                    .with_span(span)
-                }).boxed();
-
-            let mem_size = just(Token::Ctrl('?'))
-                .to(ast::MemSize::Byte)
-                .or(just(Token::Ctrl('!')).to(ast::MemSize::Word));
-
-            let memory_op = op_cast
-                .clone()
-                .then(
-                    mem_size
-                        .then(op_cast.clone())
-                        .then_ignore(just(Token::Op("=".to_string())))
-                        .then(expression.clone())
-                        .repeated(),
-                )
-                .foldl(|left, ((size, right), value)| {
-                    let span = left.span.start..value.span.end;
-                    ast::Expr::Poke {
-                        mem_location: ast::MemoryLocation {
-                            span: span.clone(),
-                            left: Box::new(left),
-                            size,
-                            right: Box::new(right),
-                        },
-                        value: Box::new(value),
-                    }
-                    .with_span(span)
-                }).boxed();
-
-            let op_product = memory_op
-                .clone()
-                .then(
-                    just(Token::Op("*".to_string()))
-                        .to(ast::BinOp::Mul)
-                        .or(just(Token::Op("/".to_string())).to(ast::BinOp::Div))
-                        .or(just(Token::Op("%".to_string())).to(ast::BinOp::Rem))
-                        .then(memory_op.clone())
-                        .repeated(),
-                )
-                .foldl(|left, (op, right)| {
-                    let span = left.span.start..right.span.end;
-                    ast::Expr::BinOp {
-                        op,
-                        left: Box::new(left),
-                        right: Box::new(right),
-                    }
-                    .with_span(span)
-                }).boxed();
-
-            let op_sum = op_product
-                .clone()
-                .then(
-                    just(Token::Op("+".to_string()))
-                        .to(ast::BinOp::Add)
-                        .or(just(Token::Op("-".to_string())).to(ast::BinOp::Sub))
-                        .then(op_product.clone())
-                        .repeated(),
-                )
-                .foldl(|left, (op, right)| {
-                    let span = left.span.start..right.span.end;
-                    ast::Expr::BinOp {
-                        op,
-                        left: Box::new(left),
-                        right: Box::new(right),
-                    }
-                    .with_span(span)
-                }).boxed();
-
-            let op_cmp = op_sum
-                .clone()
-                .then(
-                    just(Token::Op("==".to_string()))
-                        .to(ast::BinOp::Eq)
-                        .or(just(Token::Op("!=".to_string())).to(ast::BinOp::Ne))
-                        .or(just(Token::Op("<".to_string())).to(ast::BinOp::Lt))
-                        .or(just(Token::Op("<=".to_string())).to(ast::BinOp::Le))
-                        .or(just(Token::Op(">".to_string())).to(ast::BinOp::Gt))
-                        .or(just(Token::Op(">=".to_string())).to(ast::BinOp::Ge))
-                        .then(op_sum.clone())
-                        .repeated(),
-                )
-                .foldl(|left, (op, right)| {
-                    let span = left.span.start..right.span.end;
-                    ast::Expr::BinOp {
-                        op,
-                        left: Box::new(left),
-                        right: Box::new(right),
-                    }
-                    .with_span(span)
-                }).boxed();
-
-            let op_bit = op_cmp
-                .clone()
-                .then(
-                    just(Token::Op("&".to_string()))
-                        .to(ast::BinOp::And)
-                        .or(just(Token::Op("|".to_string())).to(ast::BinOp::Or))
-                        .or(just(Token::Op("^".to_string())).to(ast::BinOp::Xor))
-                        .then(op_cmp.clone())
-                        .repeated(),
-                )
-                .foldl(|left, (op, right)| {
-                    let span = left.span.start..right.span.end;
-                    ast::Expr::BinOp {
-                        op,
-                        left: Box::new(left),
-                        right: Box::new(right),
-                    }
-                    .with_span(span)
-                }).boxed();
-
-            op_bit
-        });
-
-        let block_expression = block_expression.unwrap();
-
-        expression
-            .clone()
-            .then_ignore(just(Token::Ctrl(';')))
-            .or(block_expression.map_with_span(|expr, span| expr.with_span(span)))
-            .repeated()
-            .then(expression.clone().or_not())
-            .map(|(statements, final_expression)| ast::Block {
-                statements,
-                final_expression: final_expression.map(|e| Box::new(e)),
-            })
-    })
-}
-
-fn type_parser() -> impl Parser<Token, ast::Type, Error = Simple<Token>> + Clone {
-    filter_map(|span, tok| match tok {
-        Token::Ident(id) if id == "i32" => Ok(ast::Type::I32),
-        Token::Ident(id) if id == "i64" => Ok(ast::Type::I64),
-        Token::Ident(id) if id == "f32" => Ok(ast::Type::F32),
-        Token::Ident(id) if id == "f64" => Ok(ast::Type::F64),
-        _ => Err(Simple::expected_input_found(
-            span,
-            vec![
-                Token::Ident("i32".into()),
-                Token::Ident("i64".into()),
-                Token::Ident("f32".into()),
-                Token::Ident("f64".into()),
-            ],
-            Some(tok),
-        )),
-    })
-}
-
-fn top_level_item_parser() -> impl Parser<Token, ast::TopLevelItem, Error = Simple<Token>> + Clone {
-    let integer = map_token(|tok| match tok {
-        Token::Int(v) => Some(*v),
-        _ => None,
-    });
-
-    let string = map_token(|tok| match tok {
-        Token::Str(s) => Some(s.clone()),
-        _ => None,
-    });
-
-    let identifier = map_token(|tok| match tok {
-        Token::Ident(id) => Some(id.clone()),
-        _ => None,
-    });
-
-    let import_memory = just(Token::Memory)
-        .ignore_then(integer.delimited_by(Token::Ctrl('('), Token::Ctrl(')')))
-        .map(|min_size| ast::ImportType::Memory(min_size as u32));
-
-    let import_global = just(Token::Global)
-        .ignore_then(just(Token::Mut).or_not())
-        .then(identifier.clone())
-        .then_ignore(just(Token::Ctrl(':')))
-        .then(type_parser())
-        .map(|((mut_opt, name), type_)| ast::ImportType::Variable {
-            mutable: mut_opt.is_some(),
-            name,
-            type_,
-        });
-
-    let import = just(Token::Import)
-        .ignore_then(string)
-        .then(import_memory.or(import_global))
-        .then_ignore(just(Token::Ctrl(';')))
-        .map_with_span(|(import, type_), span| {
-            ast::TopLevelItem::Import(ast::Import {
-                span,
-                import,
-                type_,
-            })
-        });
-
-    let parameter = identifier
-        .clone()
-        .then_ignore(just(Token::Ctrl(':')))
-        .then(type_parser());
-
-    let function = just(Token::Export)
-        .or_not()
-        .then_ignore(just(Token::Fn))
-        .then(identifier.clone())
-        .then(
-            parameter
-                .separated_by(just(Token::Ctrl(',')))
-                .delimited_by(Token::Ctrl('('), Token::Ctrl(')')),
-        )
-        .then(
-            just(Token::Op("->".to_string()))
-                .ignore_then(type_parser())
-                .or_not(),
-        )
-        .then(block_parser().delimited_by(Token::Ctrl('{'), Token::Ctrl('}')))
-        .map_with_span(|((((export, name), params), type_), body), span| {
-            ast::TopLevelItem::Function(ast::Function {
-                span,
-                params,
-                export: export.is_some(),
-                name,
-                type_,
-                body,
-            })
-        });
-
-    let global = just(Token::Global)
-        .ignore_then(identifier.clone())
-        .then_ignore(just(Token::Ctrl(':')))
-        .then(type_parser())
-        .then_ignore(just(Token::Ctrl(';')))
-        .map_with_span(|(name, type_), span| {
-            ast::TopLevelItem::GlobalVar(ast::GlobalVar { name, type_, span })
-        });
-
-    import.or(function).or(global)
-}
-
-fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + Clone {
-    top_level_item_parser()
-        .repeated()
-        .then_ignore(end())
-        .map(|items| {
-            let mut script = ast::Script {
-                imports: Vec::new(),
-                global_vars: Vec::new(),
-                functions: Vec::new(),
-            };
-            for item in items {
-                match item {
-                    ast::TopLevelItem::Import(i) => script.imports.push(i),
-                    ast::TopLevelItem::GlobalVar(v) => script.global_vars.push(v),
-                    ast::TopLevelItem::Function(f) => script.functions.push(f),
-                }
-            }
-            script
-        })
-}

src/typecheck.rs

@@ -1,34 +1,49 @@
+use ariadne::{Color, Label, Report, ReportKind, Source};
 use std::collections::HashMap;
 
 use crate::ast;
+use crate::Span;
 use ast::Type::*;
 
-#[derive(Debug)]
-pub struct Error {
-    pub position: ast::Position,
-    pub message: String,
+type Result<T> = std::result::Result<T, ()>;
+
+struct Var {
+    span: Span,
+    type_: ast::Type,
 }
+type Vars = HashMap<String, Var>;
 
-type Result<T> = std::result::Result<T, Error>;
-
-type Vars<'a> = HashMap<&'a str, ast::Type>;
-
-pub fn tc_script(script: &mut ast::Script) -> Result<()> {
+pub fn tc_script(script: &mut ast::Script, source: &str) -> Result<()> {
     let mut context = Context {
+        source,
         global_vars: HashMap::new(),
         local_vars: HashMap::new(),
+        block_stack: Vec::new(),
     };
 
+    let mut result = Ok(());
+
     for import in &script.imports {
         match import.type_ {
-            ast::ImportType::Variable { name, type_, .. } => {
-                if context.global_vars.contains_key(name) {
-                    return Err(Error {
-                        position: import.position,
-                        message: "Duplicate global variable".into(),
-                    });
+            ast::ImportType::Variable {
+                ref name, type_, ..
+            } => {
+                if let Some(Var { span, .. }) = context.global_vars.get(name) {
+                    result = report_duplicate_definition(
+                        "Global already defined",
+                        &import.span,
+                        span,
+                        source,
+                    );
+                } else {
+                    context.global_vars.insert(
+                        name.clone(),
+                        Var {
+                            type_,
+                            span: import.span.clone(),
+                        },
+                    );
                 }
-                context.global_vars.insert(name, type_);
             }
             // ast::ImportType::Function { .. } => todo!(),
             ast::ImportType::Memory(..) => (),
@@ -36,120 +51,261 @@ pub fn tc_script(script: &mut ast::Script) -> Result<()> {
     }
 
     for v in &script.global_vars {
-        if context.global_vars.contains_key(v.name) {
-            return Err(Error {
-                position: v.position,
-                message: "Duplicate global variable".into(),
-            });
+        if let Some(Var { span, .. }) = context.global_vars.get(&v.name) {
+            result = report_duplicate_definition("Global already defined", &v.span, span, source);
+        } else {
+            context.global_vars.insert(
+                v.name.clone(),
+                Var {
+                    type_: v.type_,
+                    span: v.span.clone(),
+                },
+            );
         }
-        context.global_vars.insert(v.name, v.type_);
     }
 
     for f in &mut script.functions {
         context.local_vars.clear();
         for (name, type_) in &f.params {
-            if context.local_vars.contains_key(name) || context.global_vars.contains_key(name) {
-                return Err(Error {
-                    position: f.position,
-                    message: format!("Variable already defined '{}'", name),
-                });
+            if let Some(Var { span, .. }) = context
+                .local_vars
+                .get(name)
+                .or_else(|| context.global_vars.get(name))
+            {
+                result =
+                    report_duplicate_definition("Variable already defined", &f.span, span, source);
+            } else {
+                context.local_vars.insert(
+                    name.clone(),
+                    Var {
+                        type_: *type_,
+                        span: f.span.clone(),
+                    },
+                );
             }
-            context.local_vars.insert(name, *type_);
         }
 
         tc_block(&mut context, &mut f.body)?;
     }
 
-    Ok(())
+    result
 }
 
 struct Context<'a> {
-    global_vars: Vars<'a>,
-    local_vars: Vars<'a>,
+    source: &'a str,
+    global_vars: Vars,
+    local_vars: Vars,
+    block_stack: Vec<String>,
 }
 
-fn tc_block<'a>(context: &mut Context<'a>, block: &mut ast::Block<'a>) -> Result<()> {
+fn tc_block(context: &mut Context, block: &mut ast::Block) -> Result<()> {
+    let mut result = Ok(());
     for stmt in &mut block.statements {
-        match *stmt {
-            ast::Statement::Expression(ref mut expr) => tc_expression(context, expr)?,
-            ast::Statement::LocalVariable(ref mut lv) => {
-                if let Some(ref mut value) = lv.value {
-                    tc_expression(context, value)?;
-                    if lv.type_.is_none() {
-                        lv.type_ = value.type_;
-                    } else if lv.type_ != value.type_ {
-                        return Err(Error {
-                            position: lv.position,
-                            message: "Mismatched types".into(),
-                        });
-                    }
-                }
-                if let Some(type_) = lv.type_ {
-                    if context.local_vars.contains_key(lv.name)
-                        || context.global_vars.contains_key(lv.name)
-                    {
-                        return Err(Error {
-                            position: lv.position,
-                            message: format!("Variable '{}' already defined", lv.name),
-                        });
-                    }
-                    context.local_vars.insert(lv.name, type_);
-                } else {
-                    return Err(Error {
-                        position: lv.position,
-                        message: "Missing type".into(),
-                    });
-                }
-            }
-            ast::Statement::Poke {
-                position,
-                ref mut mem_location,
-                ref mut value,
-            } => {
-                tc_mem_location(context, mem_location)?;
-                tc_expression(context, value)?;
-                if value.type_ != Some(I32) {
-                    return Err(Error {
-                        position,
-                        message: "Type mismatch".into(),
-                    });
-                }
-            }
+        if tc_expression(context, stmt).is_err() {
+            result = Err(());
         }
     }
     if let Some(ref mut expr) = block.final_expression {
         tc_expression(context, expr)?;
     }
-    Ok(())
+    result
 }
 
-fn tc_expression<'a>(context: &mut Context<'a>, expr: &mut ast::Expression<'a>) -> Result<()> {
+fn report_duplicate_definition(
+    msg: &str,
+    span: &Span,
+    prev_span: &Span,
+    source: &str,
+) -> Result<()> {
+    Report::build(ReportKind::Error, (), span.start)
+        .with_message(msg)
+        .with_label(
+            Label::new(span.clone())
+                .with_message(msg)
+                .with_color(Color::Red),
+        )
+        .with_label(
+            Label::new(prev_span.clone())
+                .with_message("Previous definition was here")
+                .with_color(Color::Yellow),
+        )
+        .finish()
+        .eprint(Source::from(source))
+        .unwrap();
+    Err(())
+}
+
+fn type_mismatch(
+    type1: ast::Type,
+    span1: &Span,
+    type2: Option<ast::Type>,
+    span2: &Span,
+    source: &str,
+) -> Result<()> {
+    Report::build(ReportKind::Error, (), span2.start)
+        .with_message("Type mismatch")
+        .with_label(
+            Label::new(span1.clone())
+                .with_message(format!("Expected type {:?}...", type1))
+                .with_color(Color::Yellow),
+        )
+        .with_label(
+            Label::new(span2.clone())
+                .with_message(format!(
+                    "...but found type {}",
+                    type2
+                        .map(|t| format!("{:?}", t))
+                        .unwrap_or("void".to_string())
+                ))
+                .with_color(Color::Red),
+        )
+        .finish()
+        .eprint(Source::from(source))
+        .unwrap();
+    Err(())
+}
+
+fn expected_type(span: &Span, source: &str) -> Result<()> {
+    Report::build(ReportKind::Error, (), span.start)
+        .with_message("Expected value but found expression of type void")
+        .with_label(
+            Label::new(span.clone())
+                .with_message("Expected value but found expression of type void")
+                .with_color(Color::Red),
+        )
+        .finish()
+        .eprint(Source::from(source))
+        .unwrap();
+    Err(())
+}
+
+fn unknown_variable(span: &Span, source: &str) -> Result<()> {
+    Report::build(ReportKind::Error, (), span.start)
+        .with_message("Unknown variable")
+        .with_label(
+            Label::new(span.clone())
+                .with_message("Unknown variable")
+                .with_color(Color::Red),
+        )
+        .finish()
+        .eprint(Source::from(source))
+        .unwrap();
+    Err(())
+}
+
+fn tc_expression(context: &mut Context, expr: &mut ast::Expression) -> Result<()> {
     expr.type_ = match expr.expr {
+        ast::Expr::Let {
+            ref mut value,
+            ref mut type_,
+            ref name,
+            ..
+        } => {
+            if let Some(ref mut value) = value {
+                tc_expression(context, value)?;
+                if let Some(type_) = type_ {
+                    if Some(*type_) != value.type_ {
+                        return type_mismatch(
+                            *type_,
+                            &expr.span,
+                            value.type_,
+                            &value.span,
+                            context.source,
+                        );
+                    }
+                } else if value.type_.is_none() {
+                    return expected_type(&value.span, context.source);
+                } else {
+                    *type_ = value.type_;
+                }
+            }
+            if let Some(type_) = type_ {
+                if let Some(Var { span, .. }) = context
+                    .local_vars
+                    .get(name)
+                    .or_else(|| context.global_vars.get(name))
+                {
+                    return report_duplicate_definition(
+                        "Variable already defined",
+                        &expr.span,
+                        span,
+                        context.source,
+                    );
+                }
+                context.local_vars.insert(
+                    name.clone(),
+                    Var {
+                        type_: *type_,
+                        span: expr.span.clone(),
+                    },
+                );
+            } else {
+                Report::build(ReportKind::Error, (), expr.span.start)
+                    .with_message("Type missing")
+                    .with_label(
+                        Label::new(expr.span.clone())
+                            .with_message("Type missing")
+                            .with_color(Color::Red),
+                    )
+                    .finish()
+                    .eprint(Source::from(context.source))
+                    .unwrap();
+                return Err(());
+            }
+            None
+        }
+        ast::Expr::Poke {
+            ref mut mem_location,
+            ref mut value,
+        } => {
+            tc_mem_location(context, mem_location)?;
+            tc_expression(context, value)?;
+            if value.type_ != Some(I32) {
+                return type_mismatch(I32, &expr.span, value.type_, &value.span, context.source);
+            }
+            None
+        }
         ast::Expr::I32Const(_) => Some(ast::Type::I32),
         ast::Expr::F32Const(_) => Some(ast::Type::F32),
+        ast::Expr::UnaryOp {
+            op: _,
+            ref mut value,
+        } => {
+            tc_expression(context, value)?;
+            todo!();
+        }
         ast::Expr::BinOp {
-            position,
             op,
             ref mut left,
             ref mut right,
         } => {
             tc_expression(context, left)?;
             tc_expression(context, right)?;
-            if left.type_.is_none() || left.type_ != right.type_ {
-                return Err(Error {
-                    position,
-                    message: "Type mismatch".into(),
-                });
+            if let Some(type_) = left.type_ {
+                if left.type_ != right.type_ {
+                    return type_mismatch(
+                        type_,
+                        &left.span,
+                        right.type_,
+                        &right.span,
+                        context.source,
+                    );
+                }
+            } else {
+                return expected_type(&left.span, context.source);
             }
             use ast::BinOp::*;
             match op {
                 Add | Sub | Mul | Div => left.type_,
                 Rem | And | Or | Xor => {
                     if left.type_ != Some(I32) {
-                        return Err(Error {
-                            position,
-                            message: "Unsupported type".into(),
-                        });
+                        return type_mismatch(
+                            I32,
+                            &left.span,
+                            left.type_,
+                            &left.span,
+                            context.source,
+                        );
                     } else {
                         left.type_
                     }
@@ -157,117 +313,136 @@ fn tc_expression<'a>(context: &mut Context<'a>, expr: &mut ast::Expression<'a>)
                 Eq | Ne | Lt | Le | Gt | Ge => Some(I32),
             }
         }
-        ast::Expr::Variable { position, name } => {
-            if let Some(&type_) = context
+        ast::Expr::Variable(ref name) => {
+            if let Some(&Var { type_, .. }) = context
                 .global_vars
                 .get(name)
                 .or_else(|| context.local_vars.get(name))
             {
                 Some(type_)
             } else {
-                return Err(Error {
-                    position,
-                    message: format!("Variable '{}' not found", name),
-                });
+                return unknown_variable(&expr.span, context.source);
             }
         }
         ast::Expr::LocalTee {
-            position,
-            name,
+            ref name,
             ref mut value,
         } => {
             tc_expression(context, value)?;
-            if let Some(&type_) = context.local_vars.get(name) {
+            if let Some(&Var {
+                type_, ref span, ..
+            }) = context.local_vars.get(name)
+            {
                 if value.type_ != Some(type_) {
-                    return Err(Error {
-                        position,
-                        message: "Type mismatch".into(),
-                    });
+                    return type_mismatch(type_, span, value.type_, &value.span, context.source);
                 }
                 Some(type_)
             } else {
-                return Err(Error {
-                    position,
-                    message: format!("No local variable '{}' found", name),
-                });
+                return unknown_variable(&expr.span, context.source);
             }
         }
         ast::Expr::Loop {
-            position: _,
-            label: _,
+            ref label,
             ref mut block,
         } => {
+            context.block_stack.push(label.clone());
             tc_block(context, block)?;
+            context.block_stack.pop();
             block.final_expression.as_ref().and_then(|e| e.type_)
         }
         ast::Expr::BranchIf {
-            position,
             ref mut condition,
-            label: _,
+            ref label,
         } => {
             tc_expression(context, condition)?;
             if condition.type_ != Some(I32) {
-                return Err(Error {
-                    position,
-                    message: "Condition has to be i32".into(),
-                });
+                return type_mismatch(
+                    I32,
+                    &expr.span,
+                    condition.type_,
+                    &condition.span,
+                    context.source,
+                );
+            }
+            if !context.block_stack.contains(label) {
+                Report::build(ReportKind::Error, (), expr.span.start)
+                    .with_message("Label not found")
+                    .with_label(
+                        Label::new(expr.span.clone())
+                            .with_message("Label not found")
+                            .with_color(Color::Red),
+                    )
+                    .finish()
+                    .eprint(Source::from(context.source))
+                    .unwrap();
+                return Err(());
             }
             None
         }
         ast::Expr::Cast {
-            position,
             ref mut value,
             type_,
         } => {
             tc_expression(context, value)?;
             if value.type_.is_none() {
-                return Err(Error {
-                    position,
-                    message: "Cannot cast void".into(),
-                });
+                return expected_type(&expr.span, context.source);
             }
             Some(type_)
         }
         ast::Expr::FuncCall {
-            position,
-            name,
+            ref name,
             ref mut params,
         } => {
             if let Some((ptypes, rtype)) = builtin_function_types(name) {
                 if params.len() != ptypes.len() {
-                    return Err(Error {
-                        position,
-                        message: format!(
+                    Report::build(ReportKind::Error, (), expr.span.start)
+                        .with_message(format!(
                             "Expected {} parameters but found {}",
                             ptypes.len(),
                             params.len()
-                        ),
-                    });
+                        ))
+                        .with_label(
+                            Label::new(expr.span.clone())
+                                .with_message(format!(
+                                    "Expected {} parameters but found {}",
+                                    ptypes.len(),
+                                    params.len()
+                                ))
+                                .with_color(Color::Red),
+                        )
+                        .finish()
+                        .eprint(Source::from(context.source))
+                        .unwrap();
+                    return Err(());
                 }
-                for (index, (ptype, param)) in ptypes.iter().zip(params.iter_mut()).enumerate() {
+                for (ptype, param) in ptypes.iter().zip(params.iter_mut()) {
                     tc_expression(context, param)?;
-                    if param.type_.is_none() || param.type_.unwrap() != *ptype {
-                        return Err(Error {
-                            position,
-                            message: format!(
-                                "Param {} is {:?} but should be {:?}",
-                                index + 1,
-                                param.type_,
-                                ptype
-                            ),
-                        });
+                    if param.type_ != Some(*ptype) {
+                        return type_mismatch(
+                            *ptype,
+                            &expr.span,
+                            param.type_,
+                            &param.span,
+                            context.source,
+                        );
                     }
                 }
                 rtype
             } else {
-                return Err(Error {
-                    position,
-                    message: format!("Unknown function '{}'", name),
-                });
+                Report::build(ReportKind::Error, (), expr.span.start)
+                    .with_message(format!("Unknown function {}", name))
+                    .with_label(
+                        Label::new(expr.span.clone())
+                            .with_message(format!("Unknown function {}", name))
+                            .with_color(Color::Red),
+                    )
+                    .finish()
+                    .eprint(Source::from(context.source))
+                    .unwrap();
+                return Err(());
             }
         }
         ast::Expr::Select {
-            position,
             ref mut condition,
             ref mut if_true,
             ref mut if_false,
@@ -276,40 +451,62 @@ fn tc_expression<'a>(context: &mut Context<'a>, expr: &mut ast::Expression<'a>)
             tc_expression(context, if_true)?;
             tc_expression(context, if_false)?;
             if condition.type_ != Some(ast::Type::I32) {
-                return Err(Error {
-                    position,
-                    message: "Condition of select has to be of type i32".into(),
-                });
+                return type_mismatch(
+                    I32,
+                    &condition.span,
+                    condition.type_,
+                    &condition.span,
+                    context.source,
+                );
             }
-            if if_true.type_ != if_false.type_ {
-                return Err(Error {
-                    position,
-                    message: "Types of select branches differ".into(),
-                });
-            }
-            if if_true.type_.is_none() {
-                return Err(Error {
-                    position,
-                    message: "Types of select branches cannot be void".into(),
-                });
+            if let Some(true_type) = if_true.type_ {
+                if if_true.type_ != if_false.type_ {
+                    return type_mismatch(
+                        true_type,
+                        &if_true.span,
+                        if_false.type_,
+                        &if_false.span,
+                        context.source,
+                    );
+                }
+            } else {
+                return expected_type(&if_true.span, context.source);
             }
             if_true.type_
         }
+        ast::Expr::Error => unreachable!(),
     };
     Ok(())
 }
 
 fn tc_mem_location<'a>(
     context: &mut Context<'a>,
-    mem_location: &mut ast::MemoryLocation<'a>,
+    mem_location: &mut ast::MemoryLocation,
 ) -> Result<()> {
     tc_expression(context, &mut mem_location.left)?;
     tc_expression(context, &mut mem_location.right)?;
-    if mem_location.left.type_ != Some(I32) || mem_location.right.type_ != Some(I32) {
-        return Err(Error {
-            position: mem_location.position,
-            message: "Type mismatch".into(),
-        });
+    if mem_location.left.type_ != Some(I32) {
+        return type_mismatch(
+            I32,
+            &mem_location.left.span,
+            mem_location.left.type_,
+            &mem_location.left.span,
+            context.source,
+        );
+    }
+    if let ast::Expr::I32Const(_) = mem_location.right.expr {
+    } else {
+        Report::build(ReportKind::Error, (), mem_location.right.span.start)
+            .with_message("Expected I32 constant")
+            .with_label(
+                Label::new(mem_location.right.span.clone())
+                    .with_message("Expected I32 constant")
+                    .with_color(Color::Red),
+            )
+            .finish()
+            .eprint(Source::from(context.source))
+            .unwrap();
+        return Err(());
     }
     Ok(())
 }